Hi,
Sorry you are having issues here. ..this is a complicated situation. Can I ask if these fish had any abnormal feces? When you say" getting thinner" how long did that go on? Did they lose their appetite.?
PH 9 is really high. To use buffers and pH down is not ideal..you probably get alot of precipitate.. can you use Ro water? Also with water like yours aging is probably something to consider.
Im really suspecting your issues are water related as everything started with the move..at least that what seems to be what you are saying.
Im also concerned you are using medications too much and not targeted here...to much meds makes matters worse. For now please hold off on any .